The use of copolyamides as thermoplastic adhesives has long been known. They have been found useful for bonding textiles where many modifications have been made to improve hot water resistance.
U.S. Pat. No. 3,839,121 discloses thermoplastic adhesives based on copolyamides containing branched chain diamine components which give improved resistance to washing solutions. West German Application No. 3,005,939 also discloses copolyamides containing singly branched C.sub.10 -diamines such as 5-methylnonamethylene diamine.
U.S. Pat. No. 4,566,931 describes copolyamides based on dicarboxylic acids, diamines and omega aminocarboxylic acids or lactams used to heat seal textiles, where the copolyamides comprise: (1) 20 to 80% by weight of one or more aliphatic omega aminocarboxylic acids or lactams having 6 to 12 carbon atoms in the chain; and (2) 80 to 20% by weight of equimolar mixtures o one or more aliphatic dicarboxylic acids having 6 to 12 carbon atoms with a diamine selected from aliphatic alpha-omega diamines and, optionally, cycloaliphatic diamines having 6 to 12 carbon atoms, where at least 30% by weight of these diamines consist of singly branched aliphatic diamines having 6 carbon atoms.
Semicrystalline copolyamides having a T.sub.g greater than 142.degree. C. wherein the acid is terephthalic acid or a derivative thereof are described in U.S. Pat. No. 4,937,322.
U.S. Pat. No. 4,853,460 describes polyamide adhesive compositions having a long open assembly time of at least 45 seconds wherein the acid component consists essentially of a polymeric fatty acid and a dicarboxylic acid and the amine component consists essentially of (i) a cyclic aliphatic diamine, (ii) a non-cyclic aliphatic diamine in which the amine groups are bonded to oddnumbered carbon atoms on the aliphatic chain, e.g. 2-methyl-1,5-pentanediamine, and (iii) an alkylene diamine, with or without (iv) a polyglycoldiamine.
Copolyamides have also been used as an adhesive that can be steam activated to bond ridged foam and a foam/fabric bilaminate. A copolyamide containing e-caprolactam/hexamethylenediamineadipic acid/hexamethylenediamine-sebacic acid (conventionally designated as 6/66/610) in a weight ratio of 37/28/35 (melting point, T.sub.m, about 140.degree.-145.degree. C.) can be steam activated, but contains free e-caprolactam retained from the process and, as well, continues to yield this monomer when subjected to elevated temperatures and humidity. This results in fogged windows when used for bonding interior auto components such as seating fabric, panel laminates, carpeting, etc.
The "fog" problem results from the presence of a light scattering film on the interior of an automobile windshield or other interior Window surfaces The film is caused by material transported to the window glass by distillation of volatile compounds contained in materials such as adhesives used for interior components of the automobile. Oxidation of the original condensate can contribute to the complexity of the problem.
It would be desirable to have a fog-free, rapidly heat activatable (preferably by steam heat) copolyamide adhesive composition for such uses.